Asymptotic performance of single parity-check product codes

This article investigates the asymptotic performance of single parity-check (SPC) product codes (PCs) from a decoding point of view. Specifically, the probability of bit error is bounded before and after the decoding of each dimension, similar to the analysis of "iterated codes" by Elias (1954). It is shown that the asymptotic probability of bit error can be driven to zero as the number of dimensions, and hence the block length, increases at signal-to-noise ratios (SNRs) within 2 dB of capacity over the additive white Gaussian noise (AWGN) channel.     

Absence of detectable human herpesvirus 8 in the semen of human immunodeficiency virus-infected men without Kaposi's sarcoma

The prevalence of human herpesvirus 8 (HHV-8)/Kaposi's sarcoma (KS)-associated herpesvirus was investigated in the semen of 99 human immunodeficiency virus (HIV)-infected men (median CD4 cell count, 357/mm3) by use of a polymerase chain reaction (PCR) assay capable of detecting <10 copies of HHV-8 DNA. Of the subjects, 95 (96%) self-identified as men who have sex with men (MSM), and 3 had a history of clinical KS. Seminal cell specimens were negative for HHV-8 in 98 subjects. None of the 26 without KS (27.1% of 96 tested) who were seropositive for HHV-8 by IFA for latency-associated nuclear antigens had HHV-8 detected in their semen. The only subject with any evidence for seminal HHV-8 DNA was seropositive for HHV-8 and had active KS. HHV-8 was detected in 10 (10.4%) of 96 peripheral blood mononuclear cell specimens. The prevalence of HHV-8 DNA by PCR in semen of HIV-infected MSM without KS is low.     

Information Population of an Integrated Construction Management System

This paper discusses the future requirements of integrated construction management systems and the need to support the management of large volumes of information on several levels. The solution proposes a combination of an efficient user interface and methods to partially automate the creation of the required information through access to stored information from past projects. The research follows the path being established for integrated construction management systems that rely on a standard representation of the industry's information requirements. By exploring the comprehensive aspects of construction planning for an integrated construction management system, the research demonstrates the usefulness of applying sound information representation structures. Through the application of case-based reasoning, the research advances the concepts of planning tools as they apply to integrated systems. The resulting prototype construction management system has the primary characteristic of assisting the user in the manipulation of information in order to generate the initial information requirements of an integrated construction management system.     

Some computational tools for the analysis of through cracks in stiffened fuselage shells

Reliable analytical methods that predict the structural integrity and residual strength of aircraft fuselage structures containing cracks are needed to help to understand the behavior of pressurized stiffened shells with damage, so that it becomes possible to determine the safe life of such a shell. Of special importance is the ability to determine under what conditions local failure, once initiated, will propagate. In this paper we shall present a reliable and efficient method for computing the energy release rate for cracks of varying length in a typical stiffened metallic fuselage under general loading conditions. The models used in the simulation are derived from an extensive analysis of a fuselage barrel section subjected to operational flight loads. Energy release rates are computed as a function of the length of the crack, its location, and the crack propagation mode.     

A case study of factor influencing role improvisation in crisis response teams

Common characteristics of crisis situations are ambiguous and unplanned for events. The need for improvised roles can therefore be an imperative factor for the success of an operation. The aim of this study is to deepen the understanding of the processes taking place during improvised work “as it happens”. A case study of a crisis management team at work is presented and provides an in-depth analysis of the information and communication flow of persons acting in improvised roles, including contextual factors influencing the task at hand. The analysis suggests that three main factors lay behind decreased performance by the team when some of its members were forced to take on roles for which they lacked professional training; lack of language skills, lack of domain knowledge and insufficient organizational structure of the tasks. Based on the observations from this case study, we suggest three ways of improving a team’s performance and hence resilience when forced to improvise due to lack of personnel in one or more required competence areas. These are training to take on the responsibility for tasks or roles outside ones professional area of specialization, developing formal routines for changes in roles and tasks and developing and using tools and routines for information sharing.     

Passive sensor evaluation for unmanned ground vehicle mud detection

Detecting mud hazards is a significant challenge to unmanned ground vehicle (UGV) autonomous off‐road navigation. A military UGV stuck in a body of mud during a mission may need to be sacrificed or rescued, both unattractive options. The Jet Propulsion Laboratory is currently developing a daytime mud detection capability under the U.S. Army Research Laboratory Robotics Collaborative Technology Alliances program using UGV‐mounted sensors. To perform robust mud detection under all conditions, we expect that multiple sensors will be necessary. A passive mud detection solution is desirable to meet future combat system requirements. To characterize the advantages and disadvantages of candidate passive sensors, outdoor data collections have been performed on wet and dry soil using visible, multispectral (including near‐infrared), shortwave infrared, midwave infrared, long‐wave infrared, polarization, and stereo sensors. In this paper, we examine the cues for mud detection that each of these sensors provide, along with their deficiencies, and we illustrate localizing detected mud in a world model that can used by a UGV to plan safe paths. We mostly limit our examination to mud detection during the daytime under ideal conditions: isolated wet soil surrounded by dry soil during nominal weather, i.e., no precipitation, calm wind, and near‐average temperatures. © 2010 Wiley Periodicals, Inc.     

Experimental and computational infrared imaging of bluff body stabilized laminar diffusion flames

The concept of comparing measured and computed images is extended to the mid-infrared spectrum to provide a non-intrusive technique for studying flames. Narrowband radiation intensity measurements of steady and unsteady bluff body stabilized laminar ethylene diffusion flames are acquired using an infrared camera. Computational infrared images are rendered by solving the radiative transfer equation for parallel lines-of-sight through the flame and using a narrowband radiation model with computed scalar values. Qualitative and quantitative comparisons of the measured and computed infrared images provide insights into the flame stabilization region and beyond. The unique shapes and sizes of the flames observed in the measured and computed infrared images are similar with a few exceptions which are shown to be educational. The important differences occur in the flame stabilization region suggesting improvements in thermal control of the experiment and soot formation and heat loss models.     

Roll‐to‐roll manufacturing considerations for flexible,cholesteric liquid‐crystal display (Ch‐LCD) media

Abstract— Roll‐to‐roll methods and equipment to manufacture a bistable, passively driven display media on a flexible substrate have been developed. Using continuous coating techniques and equipment, cholesteric liquid‐crystal droplets in a gelatin binder and a dark layer are simultaneously coated onto laser‐etched‐patterned transparent ITO conductors on a polymeric web. Second conductors are printed with a UV‐curable polymer thick‐film ink over the active display layers, followed by slitting and chopping to complete the manufacture of display media in a full roll‐to‐roll mode. Segmented‐ and matrix‐display media can be generated using these techniques. This paper will focus on the manufacturing considerations for producing matrix‐display media.